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<1…10111213141516…34>
  • Issue 2 headache!Ive got an issue 2 here that firstly had a blown regulator (fixed), now its reading as a 16k machine (its fully populated), ive replaced and socketed…

    ... got one or more faulty upper RAM ICs. Is P-RAMT always ... are used in generating the upper RAM control signals and a fault ... all the CPU and the upper RAM address and control lines with ... during the ROM code's RAM test and this will reveal ...
    Macc Macc August 2012 Hardware
  • Issue 2 headache!Ive got an issue 2 here that firstly had a blown regulator (fixed), now its reading as a 16k machine (its fully populated), ive replaced and socketed…

    ... problem was, as suspected, faulty upper RAM.

    Note that the ... working address found by the RAM test routine. So, for what ... try to identify the faulty RAM IC.
    Zorn Zorn August 2012 Hardware
  • Issue 2 headache!Ive got an issue 2 here that firstly had a blown regulator (fixed), now its reading as a 16k machine (its fully populated), ive replaced and socketed…

    ... a known good set of upper RAM ICs in, what value for ... the former, then swapping the RAM ICs about shouldn't make ...
    Zorn Zorn August 2012 Hardware
  • Issue 2 headache!Ive got an issue 2 here that firstly had a blown regulator (fixed), now its reading as a 16k machine (its fully populated), ive replaced and socketed…

    ... 32K (i.e. all of upper RAM), so this suggests the test ... , since that selects all of upper RAM.

    As you've ... the CPU to the appropriate upper RAM IC.
    Zorn Zorn August 2012 Hardware
  • Issue 2 headache!Ive got an issue 2 here that firstly had a blown regulator (fixed), now its reading as a 16k machine (its fully populated), ive replaced and socketed…

    Since i haven't got a continuity test on my meter (because its cheap tat) ive had to use the diode test just to see if there is any connection, pin 3 on the upper ram is displaying results on all of them
    Macc Macc August 2012 Hardware
  • Assembly game programming on ZX how-to?Hi. I'm planning to build and release new software for the Speccy but I'm pretty lame as to handle its hardware despite a good mastery of Z80 assembl…

    ... ? Like drawing the "sprites" on upper RAM and "blitting" it to the ... just after the bytes of upper line - unlike in screen memory ...
    Ralf Ralf September 2012 Development
  • Diagnosing a strange software fault in a 48kHi, A friend gave me a 48k, which I am very keen to restore. The spectrum 48k was my first computer over 20 years ago and I owe my ability to code t…

    ... employed would diagnose that any upper RAM might be bad... isn't ... yet have to test all upper rams to know which is ...
    pkersey pkersey October 2012 Hardware
  • Diagnosing a strange software fault in a 48kHi, A friend gave me a 48k, which I am very keen to restore. The spectrum 48k was my first computer over 20 years ago and I owe my ability to code t…

    ... can test either all of upper RAM or just a small area ... of lower RAM. It stripes a random sequence ... most of the common Spectrum RAM faults.
    Zorn Zorn October 2012 Hardware
  • Spectrum 16K Issue 3Hi! I just received a Spectrum 16K, which turns out to be an Issue 3. Is it really that rare? If not, I?d like to upgrade it to 48K. There are 12 em…

    ... a random value in the upper 32K (say 60000) and PEEK ... (from 0 to 255) to upper RAM in consecutive addresses, then read ... ? :) ) - modify values in upper RAM and see if other RAM addresses change when ...
    Spirantho Spirantho November 2012 Hardware
  • Spectrum 16K Issue 3Hi! I just received a Spectrum 16K, which turns out to be an Issue 3. Is it really that rare? If not, I?d like to upgrade it to 48K. There are 12 em…

    ... a random value in the upper 32K (say 60000) and PEEK ... (from 0 to 255) to upper RAM in consecutive addresses, then read ... ? :) ) - modify values in upper RAM and see if other RAM addresses change when ...
    schombi schombi November 2012 Hardware
  • My 48K Speccy has died.Hi fellow WoSer's! Wondering if you could help me with my rubber key 48k Spectrum, which died on me this afternoon. It is one I prevoiusly fixed up j…

    ... behaviour caused by bad ram. Find a RAM tester written in z80 ... was able to diagnose the upper ram of mine in this way ... turn out to be bad ram, speak to Ian from Mutant ...
    vext01 vext01 November 2012 Hardware
  • Some stupid 16K questions...Starting with... 1. Should a 16K Spectrum that's been upgraded to 48K behave [I]exactly[/I] like a 48K Spectrum? i.e. should the machine test/clear…

    Most likely a faulty 48K. You should test address 32768 with all binary bit patterns. Poking and Peeking numbers 85 and 170 might be sufficient.
    A dead (upper) RAM chip often is significant warmer as his colleagues.
    roko roko December 2012 Hardware
  • Some stupid 16K questions...Starting with... 1. Should a 16K Spectrum that's been upgraded to 48K behave [I]exactly[/I] like a 48K Spectrum? i.e. should the machine test/clear…

    It sounds like a fault in the upper RAM.

    Try this program: [url]http://www.worldofspectrum.org/forums/showthread.php?p=656549#post656549[/url]

    It'll probably let you work out which RAM ICs are faulty.
    Zorn Zorn December 2012 Hardware
  • 16k --> 48kI bought a zx and found out it was a 16k since when I execute PRINT PEEK 23733 I get 127 Does it mean I get a lesser model? What limitations do I h…

    It looks like a 48K Spectrum with an upper RAM fault. Give me a moment and I'll tell you more...
    Zorn Zorn December 2012 Hardware
  • 16k --> 48kI bought a zx and found out it was a 16k since when I execute PRINT PEEK 23733 I get 127 Does it mean I get a lesser model? What limitations do I h…

    ... suggests that bit 4 in upper RAM is stuck high.


    If the present upper RAM ICs are soldered in place ...
    Zorn Zorn December 2012 Hardware
  • 16k --> 48kI bought a zx and found out it was a 16k since when I execute PRINT PEEK 23733 I get 127 Does it mean I get a lesser model? What limitations do I h…

    ... suggests that bit 4 in upper RAM is stuck high.


    If the present upper RAM ICs are soldered in place ...
    camurso_ camurso_ December 2012 Hardware
  • 16k --> 48kI bought a zx and found out it was a 16k since when I execute PRINT PEEK 23733 I get 127 Does it mean I get a lesser model? What limitations do I h…

    ... suggests that bit 4 in upper RAM is stuck high.[/QUOTE]
    1024MAK 1024MAK December 2012 Hardware
  • TKMEM - the 128K interface for 16K SpectrumsHello all! Here in Brazil, we have made a small production of an interface, totally based on Velesoft?s memory expansion ([url]http://velesoft.speccy…

    [QUOTE=Crisis;672363]so now there is beside the 48k upgrade kit a 128k upgrade interface, wow ![/QUOTE]

    It's not perfect, but works very well.
    And you must disable the 32k upper ram. :D
    Turrican Turrican December 2012 Hardware
  • TKMEM - the 128K interface for 16K SpectrumsHello all! Here in Brazil, we have made a small production of an interface, totally based on Velesoft?s memory expansion ([url]http://velesoft.speccy…

    ... /> [/QUOTE]

    The upper 32KB of RAM must be disabled. This ... task for TK90X. If the RAM chips were plugged into sockets ... />
    I guess that the upper RAM could be easily disabled in ...
    TK90XFan TK90XFan January 2013 Hardware
  • TKMEM - the 128K interface for 16K SpectrumsHello all! Here in Brazil, we have made a small production of an interface, totally based on Velesoft?s memory expansion ([url]http://velesoft.speccy…

    ... /> Some ZX Spectrum boards have upper ram chips in sockets then is ... without sockets must be disable upper ram 32kB (for example via cut ...
    velesoft velesoft January 2013 Hardware
  • TKMEM - the 128K interface for 16K SpectrumsHello all! Here in Brazil, we have made a small production of an interface, totally based on Velesoft?s memory expansion ([url]http://velesoft.speccy…

    [QUOTE=TK90XFan;674886]The upper 32KB of RAM must be disabled. This is ... task for TK90X. If the RAM chips were plugged into sockets ... ;674886]I guess that the upper RAM could be easily disabled in ... lock the internal 32K of RAM, supply +5V on pin 4B ...
    Black_Cat Black_Cat January 2013 Hardware
  • TKMEM - the 128K interface for 16K SpectrumsHello all! Here in Brazil, we have made a small production of an interface, totally based on Velesoft?s memory expansion ([url]http://velesoft.speccy…

    ... can disable the 32k of upper RAM by a wire or jumper ...
    flopping flopping January 2013 Hardware
  • TKMEM - the 128K interface for 16K SpectrumsHello all! Here in Brazil, we have made a small production of an interface, totally based on Velesoft?s memory expansion ([url]http://velesoft.speccy…

    ... can disable the 32k of upper RAM by a wire or jumper ...
    TK90XFan TK90XFan January 2013 Hardware
  • Beta diskJust something that's been bugging me for a while, is the 128k beta disk interface wired differently to the beta 48k as a piece of hardware, or as I …

    But could an original Beta Disk interface be used with a 128k machine, for instance allowing a 128k game to be loaded by permitting paging of the upper Ram to occur?
    jamorski jamorski February 2013 Hardware
  • The new Superfo cloneHi In the spanish forum speccy.org some guys and me have optimized the superfo clon to have less ICs. The actual design has 39 ICs versus the 45 ICs…

    ... the Z80 to access the upper ram without collision. But when the ... doesn't need the video ram, the Z80 has unhindered access ... is coupled to the video ram through resistors, in this undecoded ...
    csmith csmith February 2013 Hardware
  • maximum addressable RAM for a Z80 using bank switching?What is the maximum addressable RAM for a Z80 using bank switching? The Enterprise64 home computer could address up to 4MB, is this the limit for a …

    ... 256 banks of 32K SRAM (upper RAM).
    Never made more than ... as a removable storage interface, RAM with battery or ROM cartridges ...
    Knik Knik February 2013 Hardware
  • maximum addressable RAM for a Z80 using bank switching?What is the maximum addressable RAM for a Z80 using bank switching? The Enterprise64 home computer could address up to 4MB, is this the limit for a …

    ... configure your bank switched RAM as a RAM disc, you also need ... or 48-64K in the upper RAM), the software I wrote 'saw ... ' the RAM disc as a series of ... , and dynamically mapped to the RAM disc, with used/unused sectors ...
    RST#08 RST#08 February 2013 Hardware
  • ZX8401 / PCF1306P / Amstrad 40058 for 48K and 128KZX8401 = PCF1306P = Amstrad 40058, let's get started with that. These chips are used as surrogates. Most of us might think those chips were only use…

    ... /> So that chip is for upper memory adressing, check out the ... copes with paging, leaving the upper memory logic intact, like the ... half' of the 4164/4532 upper ram chips, so Sinclair could buy ... paging ;)
    "Now that all upper ram chips we order fully work ...
    bverstee bverstee March 2013 Hardware
  • Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …

    ... suggests a fault in the upper RAM, not the lower. This is ... 're able to, try the RAM test program I created and ... . Try it against the upper and lower RAM and leave it running ...
    Zorn Zorn April 2013 Hardware
  • Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …

    Brap brap! It's faulty upper RAM:

    [IMG]http://ubuntuone.com/48eEV5ixlM8GGIlyd00iVr[/IMG]

    Thanks so much, great little utility! How do I go about identifying which IC# is the offending chip?
    junosix junosix April 2013 Hardware
<1…10111213141516…34>

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HitBox

Word Docs Hits
upper 2.8K 3.7K
ram 12.6K 21.4K
16k 5.5K 7.7K

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